/**
 * 查询模板系统
 * 提供 10 个预设模板，适配 MySQL、PostgreSQL、Redis、MongoDB 四种数据库类型
 */

export type DBType = 'mysql' | 'postgresql' | 'redis' | 'mongodb';

export type QueryTemplate = {
  id: string;
  name: string;
  description: string;
  category: string;
  sql: Partial<Record<DBType, string>>;
  supportedTypes: DBType[];
};

export const queryTemplates: QueryTemplate[] = [
  {
    id: 'table-structure',
    name: '查询表结构',
    description: '查看指定表或集合的结构定义，包括字段、类型、索引等信息',
    category: '表结构',
    sql: {
      mysql: 'SHOW CREATE TABLE {table};',
      postgresql:
        "SELECT column_name, data_type, is_nullable, column_default FROM information_schema.columns WHERE table_name = '{table}' ORDER BY ordinal_position;",
      mongodb: 'db.{collection}.getIndexes()',
    },
    supportedTypes: ['mysql', 'postgresql', 'mongodb'],
  },
  {
    id: 'table-size',
    name: '查询表大小',
    description: '查看数据库中各表或集合的存储空间占用情况',
    category: '数据统计',
    sql: {
      mysql: "SELECT table_name, data_length, index_length FROM information_schema.tables WHERE table_schema = '{db}';",
      postgresql:
        "SELECT relname, pg_relation_size(oid) FROM pg_class WHERE relkind='r';",
      redis: 'INFO memory',
      mongodb: 'db.stats()',
    },
    supportedTypes: ['mysql', 'postgresql', 'redis', 'mongodb'],
  },
  {
    id: 'active-connections',
    name: '查询活跃连接',
    description: '查看当前数据库的活跃连接数及连接详情',
    category: '性能分析',
    sql: {
      mysql: 'SHOW PROCESSLIST;',
      postgresql: 'SELECT * FROM pg_stat_activity;',
      redis: 'CLIENT LIST',
      mongodb: 'db.currentOp()',
    },
    supportedTypes: ['mysql', 'postgresql', 'redis', 'mongodb'],
  },
  {
    id: 'indexes',
    name: '查询索引',
    description: '查看指定表或集合的索引信息',
    category: '表结构',
    sql: {
      mysql: 'SHOW INDEX FROM {table};',
      postgresql:
        "SELECT * FROM pg_indexes WHERE tablename = '{table}';",
      mongodb: 'db.{collection}.getIndexes()',
    },
    supportedTypes: ['mysql', 'postgresql', 'mongodb'],
  },
  {
    id: 'lock-waits',
    name: '查询锁等待',
    description: '查看当前数据库中存在的锁等待情况，排查锁冲突',
    category: '性能分析',
    sql: {
      mysql: 'SELECT * FROM information_schema.innodb_lock_waits;',
      postgresql: 'SELECT * FROM pg_locks WHERE NOT granted;',
    },
    supportedTypes: ['mysql', 'postgresql'],
  },
  {
    id: 'top-n',
    name: 'TOP N查询',
    description: '查询指定表中按ID倒序排列的前N条记录',
    category: '基础查询',
    sql: {
      mysql: 'SELECT * FROM {table} ORDER BY id DESC LIMIT {n};',
      postgresql: 'SELECT * FROM {table} ORDER BY id DESC LIMIT {n};',
      mongodb: 'db.{collection}.find().sort({_id:-1}).limit({n})',
    },
    supportedTypes: ['mysql', 'postgresql', 'mongodb'],
  },
  {
    id: 'fuzzy-search',
    name: '模糊搜索',
    description: '根据关键词对指定字段进行模糊匹配查询',
    category: '基础查询',
    sql: {
      mysql: "SELECT * FROM {table} WHERE {column} LIKE '%{keyword}%';",
      postgresql: "SELECT * FROM {table} WHERE {column} LIKE '%{keyword}%';",
      redis: 'KEYS *{keyword}*',
      mongodb: 'db.{collection}.find({field: /{keyword}/})',
    },
    supportedTypes: ['mysql', 'postgresql', 'redis', 'mongodb'],
  },
  {
    id: 'statistics',
    name: '查询统计信息',
    description: '查看表或集合的统计信息，包括行数、大小、索引等',
    category: '数据统计',
    sql: {
      mysql: "SHOW TABLE STATUS LIKE '{table}';",
      postgresql:
        "SELECT * FROM pg_stat_user_tables WHERE relname='{table}';",
      redis: 'INFO keyspace',
      mongodb: 'db.{collection}.stats()',
    },
    supportedTypes: ['mysql', 'postgresql', 'redis', 'mongodb'],
  },
  {
    id: 'execution-plan',
    name: '查询执行计划',
    description: '查看查询语句的执行计划，用于SQL性能优化分析',
    category: '性能分析',
    sql: {
      mysql: 'EXPLAIN SELECT ...',
      postgresql: 'EXPLAIN ANALYZE SELECT ...',
      mongodb: 'db.{collection}.find({...}).explain()',
    },
    supportedTypes: ['mysql', 'postgresql', 'mongodb'],
  },
  {
    id: 'redis-get',
    name: 'GET 查询',
    description: '获取 Redis String 类型 key 的值',
    category: '基础查询',
    sql: { redis: 'GET {key}' },
    supportedTypes: ['redis'],
  },
  {
    id: 'redis-hgetall',
    name: 'HGETALL 查询',
    description: '获取 Redis Hash 类型 key 的所有字段和值',
    category: '基础查询',
    sql: { redis: 'HGETALL {key}' },
    supportedTypes: ['redis'],
  },
  {
    id: 'redis-hget',
    name: 'HGET 查询',
    description: '获取 Redis Hash 类型 key 中指定字段的值',
    category: '基础查询',
    sql: { redis: 'HGET {key} {field}' },
    supportedTypes: ['redis'],
  },
];

/**
 * 获取模板在指定数据库类型下的查询语句
 * 自动替换占位符: {table} → 当前选中的表, {db} → 当前数据库, {collection} → 集合名
 */
export function getTemplateSQL(
  template: QueryTemplate,
  dbType: DBType,
  vars?: { table?: string; db?: string; collection?: string }
): string {
  const sql = template.sql[dbType];
  if (!sql) {
    return `-- 当前模板「${template.name}」不支持 ${dbType} 数据库类型`;
  }
  let result = sql;
  const v = vars || {};
  if (v.table) result = result.replace(/\{table\}/g, v.table);
  if (v.db) result = result.replace(/\{db\}/g, v.db);
  if (v.collection) result = result.replace(/\{collection\}/g, v.collection);
  // 未替换的占位符保留，用户手动填写
  return result;
}

/**
 * 获取指定数据库类型支持的所有模板
 * @param dbType 数据库类型
 * @returns 该数据库类型支持的模板列表
 */
export function getTemplatesForType(dbType: DBType): QueryTemplate[] {
  return queryTemplates.filter((template) =>
    template.supportedTypes.includes(dbType)
  );
}